Access openings, for example, in warehouse, manufacturing and industrial settings are often secured by overhead (vertically traveling) closures. One popular type of overhead closure is a coiling closure, for example, mesh or slatted doors, such as rolling steel doors. These closure types move in a generally vertical path coiling above the opening as the door is opened. Because overhead coiling closures have many fewer parts than other door types with less risk for damage and inoperability, they often make a better solution for facilities that cannot afford opening downtime.
An overhead coiling closure is generally provided with a powered operator to power the door to an open or closed position, manually opened and closed with, for example, a looped chain or crank, or is hand lifted aided by spring tension. A shaft is horizontally mounted above the access opening to wind or unwind the coiling closure. The coiling shaft and operator (if present) are usually covered by a hood.
Another popular type of overhead closure is a sectional overhead door. Sectional overhead doors are manufactured from horizontally hinged panels that roll into an overhead position on tracks, usually spring-assisted. Each panel of the sectional overhead door has its own connection to the door track. This increases reliability and robustness compared to monolithic doors which have only a couple of track connections for the whole panel.
A sectional overhead door may be provided with a powered operator (motor) operatively connected to a panel to power the door to an open or closed position, or it may be manually opened and closed, for example with a handle.
Both coiling and sectional closures use a pair of tracks or door guides mounted to the structure at opposite sides of the access opening. In addition to providing operative guidance, the guides insure the closure can act as a secure barrier to prevent unauthorized entry when closed.
For many applications the locking capability provided by the operator alone is not sufficient. Consequently it is necessary to provide additional locking to achieve required security.
Closure designs attempt to minimize the chance for catastrophic displacement, either intentional or unintentional, of the door from the door guide, which would allow unwanted or unauthorized entry. For example, when struck, the door will bow and if the displacement force is great enough the door can dislodge from its guide, allowing passage between the door and side wall, thereby no longer providing a secure barrier.
Accordingly, there is a continuing need for improved door protection designs. The present invention fulfills this need and further provides related advantages.